With the recent tendency toward downsizing and increase in circuit integration of information communication appliances, the inner semiconductor packages for the appliances are being changed from lead frame-type packages to new-type high-density semiconductor packages such as BGA, CSP; and for example, for bonding a semiconductor chip to a circuit board or for bonding plural circuit boards together, use of a patterned adhesive is proposed (for example, see Reference 1).
In general, however, a photosensitive adhesive composition heretofore known in the art is patterned by exposing it to light and developing it, whereupon the resin used in the composition is crosslinked and cured. Accordingly, when an object is adhered to the thus-patterned adhesive composition layer, then it must be applied to the layer under thermal pressure at a high temperature. In addition, as so mentioned hereinabove, the conventional photosensitive adhesive composition is crosslinked and cured when it forms a pattern, and therefore even when an object is applied to the patterned layer under thermal pressure at such a high temperature, the adhesive composition could not be fully fluid even though it may be softened in some degree, and, as a result, there may occur partial voids in the adhesive interface between the adhesive and the object to be adhered. In general, therefore, it is difficult to obtain a sufficient adhesion strength between the adhesive and the object. Needless-to-say, semiconductor chips and circuit boards that are to be bonded with such an adhesive are damaged by heat, and primarily therefore, their adhesion at a high temperature must be preferably avoided, as mentioned above.
Reference 1: JP-A-2003-297876